Reproducing device

ABSTRACT

A reproducing device for playing back data from a recording medium, including: play back circuits for reading first stream data, which includes first video data, first audio data, and first subpicture data, from a recording medium; download data storage circuits for storing second stream data, which includes at least one of second video data, second audio data and second subpicture data downloaded via a network; and selection circuits for conducting at least one of: switching from said first video data to said second video data; switching from said first audio data to said second audio data, and switching from said first subpicture data to said second subpicture data; wherein data which is newly switched by said selection circuits and data which is not switched by said selection circuits are synchronously superimposed and outputted.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 10/960,059, filedOct. 8, 2004, now U.S. Pat. No. 7,835,626 which relates to applicationSer. No. 12/058,879, filed Mar. 31, 2008 and application Ser. No.12/058,888, filed Mar. 31, 2008. This application relates to and claimspriority from Japanese Patent Application No. 2003-351510, filed on Oct.10, 2003. The entirety of the contents and subject matter of all of theabove is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a playback technique for reading datafrom an optical disk or other recording medium and reproducing picturesand sound, and, more particularly, the invention relates to a playbacktechnique that is capable of simultaneously playing back data reproducedfrom a recording medium and data downloaded via a network.

The use of a DVD or other similar recording medium makes it possible todistribute/sell motion pictures and other video content with ease. Theuser can play back such a recording medium using a reproducing device ata desired time. Not only video and audio data, but also sub-picture dataand other additional data is recorded as a video content. The additionaldata is reproduced and displayed as needed together with the video andaudio data.

Further, a technology disclosed, for instance, by Japanese PatentLaid-open No. Hei 7-30814 is capable of receiving an audio datatransmission, to which multi-language sub-picture data is added, and ofdisplaying a subtitle on a screen in a user-selected language.

SUMMARY OF THE INVENTION

Meanwhile, there is a scheme for downloading sub-picture data and otheradditional data via a network. For instance, if sub-picture data for adifferent language is downloaded for use, it is possible to use such alanguage even if it is not prerecorded on a disk. Since such a schemeeliminates the need for prerecording sub-picture data for a plurality oflanguages, it is possible to reduce the disk preparation cost andperiod.

The recording capacity of the disk is limited. If the user downloadsonly the subtitle and audio data for a required language after diskacquisition, there is no need to prerecord unnecessary data on the disk,thereby making it possible to effectively use the space on the disk.

When the data recorded on the disk and the data downloaded via a networkare to be synchronously output, it is necessary to change data that hasbeen entered into an audio decoder, sub-picture decoder, or otherdecoder. More specifically, it is necessary to choose between the use ofthe audio data recorded on the disk or the use of the downloaded audiodata.

It is an object of the present invention to provide a playback techniquefor playing back video, audio, and sub-picture data in an arbitrarycombination when the video, audio, and sub-picture data are enteredthrough two channels.

To solve the above-described problems, the present invention provides areproducing device, which comprises playback circuits, download datastorage circuits, and selection circuits. The playback circuit readsfirst stream data, which includes first video data, first audio data,and first sub-picture data, from a recording medium. The download datastorage circuit stores second stream data, which includes second videodata, second audio data, and second sub-picture data downloaded via anetwork. The selection circuits switch from the first video data to thesecond video data, from the first audio data to the second audio data,and/or from the first sub-picture data to the second sub-picture data.The reproducing device synchronously outputs the data newly selected bythe selection circuits and the data continuously selected by theselection circuits.

The second stream data may be the data that was reproduced from a secondrecording medium and not downloaded data. Further, the second streamdata may also be the data that is recorded on the same recording mediumas for the first stream data and was subjected to time-multiplexedplayback.

When video, audio, and sub-picture data are entered through twochannels, the present invention makes it possible to play back thevideo, audio, and sub-picture data in an arbitrary combination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the structure of a packetswitcher according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating the structure of a reproducingdevice.

FIG. 3 is a diagram which illustrates the stream structure and packetstructure.

FIG. 4 is a block diagram illustrating the structure of a packetswitcher according to a second embodiment of the present invention.

FIG. 5 is a block diagram illustrating the structure of a packetswitcher according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various embodiments of the present invention will now be described.

FIG. 1 is a block diagram illustrating the structure of a packetswitcher 100 according to a first embodiment of the present invention.

The packet switcher 100 includes a download stream data input terminal101, a control signal input terminal 102, buffer memories 103 a to 103d, selector switches 104 a to 104 d, a playback stream data inputterminal 105, another buffer memory 106, a demultiplexer 107, and packetoutput terminals 108 a to 108 d.

The buffer memory 103 a buffers audio packets within downloaded streamdata; a selector switch 104 a is operated for making an audio packetselection; and an audio packet output terminal outputs the audiopackets. The reference numerals 103 b, 104 b, and 108 b denote similarelements which form a video packet output system. Similarly, thereference numerals 103 c, 104 c, and 108 c denote elements which form asubtitle packet output system. The reference numerals 103 d, 104 d, and108 d denote elements of a graphics packet output system.

FIG. 2 is a block diagram illustrating the structure of a reproducingdevice according to the present invention. The following descriptionassumes that the reproducing device is equipped with the packet switcher100 shown in FIG. 1. The block diagram in FIG. 2 also shows various dataflows. The components of the reproducing device are controlled by asystem controller 205.

In FIG. 2, the reproducing device includes the packet switcher 100; anetwork input/output terminal 201; a network controller 202; a datarecording unit 203; an optical disk reproducing unit 204; a systemcontroller 205; an audio decoder 206; an audio output terminal 207; avideo decoder 208; a sub-picture decoder 209; a graphics decoder 210; avideo synthesizer 211; and an video output terminal 212.

FIG. 3 illustrates the structure of stream data. The stream dataaccording to the present embodiment comprises a plurality of 188-byteMPEG packets to which 4-byte header data is attached. The 4-byte headerdata includes a 30-bit timestamp (time data).

The MPEG packets are not always contiguous when transferred. When theamount of data is small, the packet intervals are increased. When theamount of data is large, on the other hand, the packet intervals aredecreased. At the time of stream file recording, the recording time ofeach entered MPEG packet is attached to each packet and is recorded as atimestamp. At the time of playback, the timestamp is used to reproducethe packet transfer intervals by adjusting the output timing of eachpacket.

The leading end of each MPEG packet contains 13-bit packet IDinformation, which is referred to as a PID (Packet IDentifier). The PIDhas a number that varies with the packet type. When the PID is checked,it is easy to determine the type of data contained in each packet.

The data recorded on an optical disk and the data downloaded via anetwork are both in a stream data format, as shown in FIG. 3.

First of all, the operation to play back the data recorded on an opticaldisk without using the downloaded data will be described.

In the optical disk reproducing unit 204, an optical disk is set onwhich the data necessary for playing back contents (motion picture,etc.), such as video, audio, and sub-picture data, are recorded.

A user enters a playback start command with a playback button on aremote controller (not shown). When the playback start command entersthe system controller 205 via a remote controller receiver (not shown),the system controller 205 controls the optical disk reproducing unit 204in order to start playing back the data from the optical disk.

More specifically, the file management data recorded on the optical diskis first read. The file management data contains the filenames (fileidentifiers) of all of the files recorded on the optical disk, therecording start sector location of each file, the data length of eachfile, and attribute data about each file. When these data are used, thesystem controller 205 can handle the data recorded on the optical diskas files.

After the file management data is acquired, the files required forcontent playback are sequentially read. The files to be sequentiallyread include a play list file, which indicates the order in which thefiles are to be played back; a menu data file, which displays a menuscreen; and a stream file, which contains actual stream recordings.

The system controller 205 causes display circuits (not shown) to open amenu screen by using the menu data file for the purpose of allowing theuser to select a desired content stream file.

For stream playback purposes, the optical disk reproducing unit 204reads the stream file from the optical disk. The read stream file ishandled as stream data and is entered into the buffer memory 106 via theinput terminal 105 of the packet switcher.

The stream data reproduced from the optical disk is recorded in a packetformat, as shown in FIG. 3. A 30-bit timestamp is attached to eachpacket as time data.

The stream data entered into the buffer memory 106 is output from thebuffer memory 106 in accordance with the time indicated by the timestampattached to each packet, and it is then entered into the demultiplexer107. At this time, the timestamp is removed so that a 188-byte MPEGpacket enters the demultiplexer 107.

In the demultiplexer 107, each entered packet is demultiplexed into avideo packet, an audio packet, a subtitle packet, and a graphics packet,depending on the PID, and then the packet is output.

As indicated in FIG. 3, the leading end of each MPEG packet contains a13-bit PID (packet identification number). This PID is used for packetdemultiplexing. It is assumed that the relationship between each PID andthe data is predefined.

The signals derived from the demultiplexing process performed by thedemultiplexer 107 are output to output terminals 108 a through 108 d viathe selector switches 104 a to 104 d, respectively. When the data on theoptical disk is to be used, the selector switches 104 a to 104 d arecontrolled so as to select the output of the demultiplexer 107.

The audio packet, which is derived from the demultiplexing processperformed by the demultiplexer 107, is output to output terminal 108 aand then input into the audio decoder 206. The audio decoder 206 decodesthe audio packet and generates an audio signal from the audio outputterminal 207.

The video packet enters the video decoder 208 via output terminal 108 b.Similarly, the subtitle packet enters the sub-picture decoder 209 viaoutput terminal 108 c, and the graphics packet enters the graphicsdecoder 210 via output terminal 108 d.

The decoded video data, which is generated by the video decoder 208, thedecoded sub-picture data, which is generated by the sub-picture decoder209, and the decoded graphics data, which is generated by the graphicsdecoder 210, are synthesized by the video synthesizer 211, whichperforms a superimposition. The resulting synthesized data is outputfrom the video output terminal 212. The video signal output in thismanner is then displayed on an external television screen or the like.

As described above, various data recordings on the optical disk arereproduced and then output as an audio signal and a video signal.

The operation performed for downloading stream data and synchronouslyplaying back the downloaded stream data and the stream data recorded onthe optical disk will now be described.

If user-desired sub-picture data or audio data is not recorded on theoptical disk, the user downloads the sub-picture data and audio data viathe network controller 202. The user operates the remote controller (notshown) to issue an instruction for a download and sends a download startcommand to the system controller 205.

Upon receipt of the download start command, the system controller 205connects to a network by using the download data recorded on the opticaldisk that is inserted into the optical disk reproducing unit 204, andattempts to perform a download. The download data contains the URL(Unified Resource Locator) of a connection destination server. Theconnection to a networked server is established in accordance with theURL.

A list of downloadable data is supplied to the networked server. Listedgraphics data is transferred via the network input/output terminal 201,network controller 202, system controller 205, graphics decoder 210,video synthesizer 211, and video output terminal 212, and then it isdisplayed on an external television screen or the like. The user canview the listings displayed on the screen and select the data to bedownloaded.

The data selected by the user is handled as stream data and istransmitted from the server to the reproducing device via the network.The network controller 202 stores the received stream data in the datarecording unit 203.

The stream data to be downloaded contains audio data, sub-picture data,graphics data, and video data. This data can be individually downloadedin accordance with a user selection. The user may download only onestream data or a plurality of stream data. Downloaded stream data is tobe stored in the data recording unit 203.

The data recording unit 203 may be a storage medium, such as a hard diskdrive, or a semiconductor memory device, such as a RAM or a flashmemory.

The downloaded stream data is similar to the stream data that isrecorded on the optical disk, and it is encoded as an MPEG packetcontaining a timestamp. After completion of the stream data download,the data on the optical disk and the downloaded stream data aresynchronously played back.

First of all, the user presses a playback start button (not shown) onthe remote controller to enter an optical disk playback start command.The system controller 205 receives the user's playback start command andstarts to perform a playback operation. Since the downloaded stream datais recorded in the data recording unit 203 at this stage, the systemcontroller 205 opens a confirmation window on an external televisionscreen or the like via the graphics decoder 210, video synthesizer 211,and video output terminal 212, thereby asking the user whethersynchronous playback is needed. If the user selects a synchronousplayback option, the system controller 205 plays back the downloadedstream data, which is stored in the data recording unit 203, insynchronism with the playback of the stream data on the optical disk.

Thus, the specified stream data is reproduced from the optical disk. Thereproduced stream data then enters the buffer memory 106 via the inputterminal 105 of the packet switcher 100. The stream data entered in thebuffer memory 106 is input into the demultiplexer 107 at a timeaccording to the timestamp, demultiplexed into an audio packet, videopacket, subtitle packet, and graphics packet in accordance with the PID,and entered respectively into selector switches 104 a through 104 d.

Meanwhile, the stream data that is stored in the data recording unit 203and designated for synchronous playback is read from the data recordingunit 203 and input into buffer memories 103 a through 103 d via theinput terminal 101 of the packet switcher. The system controller 205issues an instruction via input terminal 102 to specify which buffermemory (102 a to 103 d) is to be written into. The system controller 205simultaneously carries out data read control, which controls theabove-mentioned reading of data from the data recording unit 203, anddata write control, which controls the writing of data into buffermemories 103 a through 103 d.

For ease of explanation, the following description assumes that thedownloaded sub-picture data and audio data and the video data on theoptical disk are to be synchronously played back.

The stream data for synchronous playback is read from the data recordingunit 203 on an individual packet basis and is written into buffer memory103. This stream data read operation is performed for each stream datatype according to the PID. The subtitle packet is written into buffermemory 103 c, whereas the audio packet is written into buffer memory 103a. In these operations, the packets are read from the data recordingunit 203 and written into buffer memories 103 a and 103 c in a timedivision multiplexed manner so as to prevent buffer memories 103 a and103 c from overflowing. In time division multiplexing, the operation forwriting the audio packet into buffer memory 103 a and the operation forwriting the subtitle packet into buffer memory 103 c are repeatedlyperformed. The system controller 205 performs the reading from the datarecording unit 203 and the writing into the buffer memories 103 a and103 c.

Buffer memory 103 a, which handles audio data, adjusts the audio packetoutput timing in accordance with the timestamp of each audio packetbeing written. The audio packets enter selector switch 104 a from buffermemory 103 a with a predetermined timing. A 4-byte header, whichincludes a timestamp, is removed from each audio packet when it entersthe selector switch 104 a.

Similarly, buffer memory 103 c, which handles sub-picture data, adjuststhe output timing of each subtitle packet, and enters subtitle packetsinto selector switch 104 c.

Meanwhile, the stream data reproduced from the optical disk enters thebuffer memory 106 via input terminal 105. The buffer memory 106 outputspackets with a predetermined timing according to the timestamp attachedto each packet. Multiplexing is performed so that the stream datareproduced from the optical disk contains a video packet, an audiopacket, a subtitle packet, and a graphics packet.

The stream data output from the buffer memory 106 enters thedemultiplexer 107 with a predetermined timing according to thetimestamp. The demultiplexer 107 demultiplexes the entered stream data,separates it into various types of data packets, and enters themrespectively into selector switches 104 a through 104 d.

Buffer memories 103 a through 103 d and the buffer memory 106 adjust theoutput timing so as to synchronously play back the downloaded data andthe data on the optical disk.

When downloaded stream packets are to be played back, selector switches104 a through 104 d perform switching operations so as to select theoutputs from buffer memories 103 a through 103 d. When the stream dataon the optical disk is to be played back, selector switches 104 athrough 104 d perform switching operations so as to select the output ofthe demultiplexer 107.

When the downloaded sub-picture data and audio data and the video dataand graphics data on the optical disk are to be synchronously playedback, selector switch 104 c, which handles subtitle packets, andselector switch 104 a, which handles audio packets, are set to buffermemories 103 c and 103 a, respectively, and selector switch 104 b, whichhandles video packets, and selector switch 104 d, which handles graphicspackets, are set to the demultiplexer 107. Selector switches 104 athrough 104 d are operated in the above-described manner by the systemcontroller 205.

Selector switch 104 a selects the output of buffer memory 103 a andenters it into the audio decoder 206. In other words, the downloadedaudio packets, which are stored in the data recording unit 203, areinput, decoded, and output to the audio output terminal as audio data.

Selector switch 104 b selects the output of the demultiplexer 107 andenters it into the video decoder. In other words, the video packetsreproduced from the optical disk are input, decoded, and input into thevideo synthesizer 211 as video data.

Selector switch 104 c selects the output of buffer memory 103 c andenters it into the sub-picture decoder 209. In other words, thedownloaded subtitle packets, which are stored in the data recording unit203, are input, decoded, and input into the video synthesizer 211 assub-picture data.

Another selector switch selects the output of the demultiplexer 107 andenters it into the graphics decoder 210. In other words, the graphicspackets reproduced from the optical disk are input, decoded, and inputinto the video synthesizer 211 as graphics data.

In the video synthesizer 211, decoded video data, subtitle video data,and graphics video data are entered, subjected to a superimpositionprocess (superimpose), and are output as a video signal. The outputvideo signal is transferred out from the video signal output terminaland displayed on an external television screen or the like.

As described above, the stream data reproduced from the optical disk andthe downloaded stream data can be synchronously played back.

The foregoing embodiment assumes that an optical disk is used as acontents recording medium. However, the present invention is not limitedto the use of an optical disk, but is also applicable to the use of amagnetic recording medium or a semiconductor recording medium, etc.

In the reproducing device shown in FIG. 2, the optical disk reproducingunit 204 is separated from the data recording unit 203. Alternatively,however, these components may be integrated into a single unit. Forexample, the optical disk may be provided with a recording area, whichis used as the data recording unit 203. In a read process, the streamdata prerecorded on the optical disk and the stream data downloaded viaa network may be read in a time division manner and entered into thepacket switcher 100.

It has been assumed in the description of the foregoing embodiment thatthe stream data downloaded through a network and the stream datareproduced from the optical disk are synchronously played back.Alternatively, however, the reproducing device shown in FIG. 2 may beconfigured so that the network input/output terminal 201, networkcontroller 202, and data recording unit 203 are replaced by anotheroptical disk unit to synchronously play back the stream data reproducedby two optical disk units.

In the packet switcher 100 shown in FIG. 1, all data types are providedwith separate specific buffer memories, which are used to buffer variouspackets and adjust their output timing. However, the provision of aplurality of buffer memories is at a disadvantage because it increasesthe circuit scale. The block diagram in FIG. 4 illustrates analternative packet switcher that is capable of performing operationswith a single memory to produce results that are equivalent to thoseobtained from the use of a plurality of buffer memories. Thisalternative packet switcher reduces the circuit scale.

In FIG. 4, the reference numeral 401 denotes a RAM (Random AccessMemory), and the reference numeral 402 denotes a RAM read controller.The packet switcher shown in FIG. 4 is equipped with the RAM 401 and RAMread controller 402, instead of a plurality of buffer memories.

In a stream file data write process, the stream data is written into theRAM 401. The stream data write address to be used is controlled by thesystem controller 205. When a plurality of stream data are to be writteninto the RAM 401, the RAM 401 may be divided for use.

The stream data written in the RAM 401 is read by the RAM readcontroller 402. The RAM read controller 402 reads packets in variousareas of the RAM 401 in accordance with the time indicated by atimestamp that is attached to each packet, and it supplies the readpackets to selector switches 104 a through 104 d. In this instance, theRAM read controller 402 does not read the headers, which containtimestamps, and it outputs only the 188-byte MPEG packets to selectorswitches 104 a through 104 d.

As is the case with the use of the packet switcher 100 shown in FIG. 1,selector switches 104 a through 104 d selectively output the stream datareproduced from the data recording unit 203 and the stream datareproduced from the optical disk.

As described above, the use of one RAM instead of a plurality of buffermemories provides the same advantages as the first embodiment andreduces the circuit scale as well.

In the reproducing device shown in FIG. 2, the packet switcher 100 maybe replaced by the packet switcher 100 shown in FIG. 5. In the latterpacket switcher 100, buffer memories 102 and 106 and demultiplexers 501and 107 are provided for both the processing system for the downloadedstream data, which is input from the input terminal 101, and theprocessing system for the stream data derived from the disk, which isinput to the input terminal 105. The employed configuration is such thatthe outputs of demultiplexers 501 and 107 are selected as needed usingselector switches 104 a and 104 c. In the present embodiment, the streamdata to be downloaded comprises sub-picture data and audio data.Therefore, the employed configuration makes it possible to select theoutputs of these two types of data.

If the employed configuration permits demultiplexer 501 to select videodata and graphics data while a selector switch is provided to switchbetween the outputs of demultiplexers 501 and 107, which relate to videodata and graphics data, it is possible to obtain the same functionalityas that of the packet switcher shown in FIGS. 1 and 4.

1. A reproducing device for playing back data from a recording medium,comprising: play back circuits for reading first stream data from arecording medium, the first stream data including first video data,first subtitle data, and first graphics data and having a plurality ofpackets, each packet having a packet identification information;download data storage circuits for downloading and storing second streamdata, via a network, the second stream data including second video data,second subtitle data and second graphics data and having a plurality ofpackets, each packet having the packet identification information; afirst switcher for selecting the first video data, the first subtitledata or first graphics data from the first stream data read by the playback circuits based on the packet identification information; a secondswitcher for selecting second video data, second subtitle data or secondgraphics data from the second stream data downloaded and stored by thedownload data storage circuits based on the packet identificationinformation; selection circuits for conducting plural selectionsincluding a first selection to select between the first video dataselected by the first switcher and the second video data selected by thesecond switcher, a second selection to select between the first subtitledata selected by the first switcher and the second subtitle dataselected by the second switcher, and a third selection to select betweenthe first graphics data selected by the first switcher and the secondgraphics data selected by the second switcher, where the first, secondand third selections are able to perform selection independently fromeach other; output circuits for outputting the video data, the subtitledata and the graphics data selected by the selection circuits; whereinthe first stream data arid the second stream data are reproducedsynchronously; and wherein the video data, the subtitle data and thegraphics data from the selection circuits are superimposed together witheach other and outputted.
 2. A reproducing method of playing back datafrom a recording medium, comprising: reading first stream data from arecording medium, the first stream data including first video data,first subtitle data, and first graphics data and having a plurality ofpackets, each packet having a packet identification information;downloading and storing second stream data via a network, the secondstream data including second video data, second subtitle data and secondgraphics data and having a plurality of packets, each packet having thepacket identification information; selecting the first video data, thefirst subtitle data or first graphics data from the read first streamdata based on the packet identification information; selecting secondvideo data, second subtitle data or second graphics data from thedownloaded and stored second stream data based on the packetidentification information; conducting plural selections including afirst selection to select between the selected first video data and theselected second video data; a second selection to select between theselected first subtitle data and the selected second subtitle data, anda third selection to select between the selected first graphics data andthe selected second graphics data, where the first, second and thirdselections are able to perform selection independently from each other;and outputting the video data, the subtitle data and the graphics dataselected by the first, second and third selections; wherein the firststream data and the second stream data are reproduced synchronously; andwherein the video data, the subtitle data and the graphics data aresuperimposed and outputted selected by the first, second and thirdselections.